Chain saw bow

ABSTRACT

A new and improved bow for use on chain saws, the bow frame of which is circular in shape to permit multiple locations for selectively fitting spurs to the bow as the bow wears during use. The bow is formed of four separate, replaceable parts, and can be removably fitted to substantially any chain saw while in the field.

United States Patent 1191 1111 3,921,291 Henley Nov. 25, 1975 [54] CHAIN SAW BOW 2,804,105 8/1957 Stone 30/382 x 3,182,695 5/1965 Ri oni.... [76] Inventor: Louis L. Henley, 3617 Maywood 3,247,873 4/1966 Aigken Drlve, Shreveport, 71109 3,590,892 7/1971 Ehlen 30/380 22 Filed: Mar. 28, 1975 Primary Examiner-Al Lawrence Smith PP 563,215 Assistant Examiner-J. C. Peters Attorney, Agent, or Firm-John M. Harrison [52] US. Cl 30/382; 30/387 51 1m. (:1. B27B 17/06 [571 ABSTRACT [58] Field of Search 30/380, 381, 382, 383, A n n pr w f r use n chain saws, he

30/384, 385, 386, 387; 83/830, 831, 832, bow frame of which is circular in shape to permit mul- 833, 834 tiple locations for selectively fitting spurs to the bow as the bow wears during use. The bow is formed of [56] References Cited four separate, replaceable parts, and can be remov- UNITED STATES PATENTS ably fitted to substantially any chain saw while in the 2,618,298 11/1952 Pratt 30/386 field 2,731,048 1/1956 Seizert 30/385 10 Claims, 5 Drawing Figures US. Patent Nov. 25, 1975 3,921,291

/ [II I CHAIN SAW BOW BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a new and improved chain saw bow, and particularly, to a new and improved bow having a circular shaped bow frame which may be adjusted into multiple cutting positions as the bow frame wears. The bow is formed of a mount plate, a pair of chain guards and a bow frame, the latter of which is circular in shape to permit relocation of the spurs as the bow wears during use.

2. Description of the Prior Art Heretofore, chain saw bows have been designed in an essentially teardrop shape, with the cutting chain traversing the outer periphery of the bow and the spur or bumper attached to the curved bottom section of the bow to stabilize the cutting operation. The bow frame and mount plate are generally designed as a single unit and the bow is removably fitted to the chain saw by means of bolts. Furthermore, when the bow frame wears to an undesirable extent at a point forward of the spurs as a result of cutting use, the symmetrically shaped bow may be reversed from top to bottom in the chain saw and the spurs relocated at a point of the unworn opposite section of the bow. This reversal increases bow life by a factor of two, since both sides of the bow frame may be used in cooperation with the spurs until badly worn, at which time the bow is removed from the saw and discarded.

Accordingly, a disadvantage of conventional chain saw bows lies in the fact that such bows may be used only for a relatively short period of time under ordinary working conditions until both spur locations are badly worn and the bow must be discarded. A further disadvantage of conventional chain saw bows lies in the tendency of the bow to break due to vibration and also when the bow is caught in a bind during the cutting operation and pressure is brought to bear during removal. This problem of bow failure frequently results in significant lost time on the job since the broken bow must either be welded or replaced before additional cutting can be accomplished. Another disadvantage of conventional chain saw bows lies in the requirement that the entire bow be hand crafted, and the outer peripheral edge of the bow be fashioned from a strip of high carbon, hard steel, which must in turn be welded to the bow in order to provide a seat of suitable hardness and wear-resistance for the moving chain. The bow must then be smoothed in a grinding operation and painted. In view of the necessity for welding the chain seat in place and effecting the grinding operation, conventional chain saw bows are susceptible of minimal automation and are therefore expensive.

Accordingly, it is an object of the present invention to provide a new and improved chain saw bow, the frame of which is circular in shape and includes multiple mounting positions which can be utilized for the bow spurs as the bow frame wears during the cutting operation.

Yet another object of the invention is to provide a new and improved chain saw bow frame which is circular in shape and which may be used several times as long as conventional chain saw bows without the neces sity of discarding the bow or bow frame.

A still further object of the invention is to provide a new and improved chain saw bow frame, the outer pc- 2 ripheral surface of which may be heat treated by open flame without the necessity of welding an external, hard metal strip around the periphery of the frame to seat and carry the chain.

Yet another object of the invention is to provide a new and improved chain saw bow, the bow frame of which may be quickly and easily removed when damaged or broken and a new frame inserted and bolted in place in the field.

A still further object of the invention is to provide a new and improved chain saw bow, the engine mount plate, bow frame and chain guards of which are independently and removably mounted, thereby allowing replacement of the bow frame, either/or both of the chain guards, and the engine mount plate, each independently of the other.

A still further object of the invention is to provide a new and improved chain saw bow which includes a bow frame, a pair of chain guards and an engine mount plate, each of which component parts can be separately replaced independently of the other component parts.

Yet another object of the invention is the provision of a new and improved chain saw bow frame which can be utilized when broken and which can be quickly and easily replaced in the field.

Another object of the invention is to provide a new and improved chain saw bow frame which is circular in shape and which is removably carried by a pair of chain guards, which chain guards are, in turn, removably carried by an engine mount plate.

SUMMARY OF THE INVENTION These and other objects of the invention are provided in a new and improved chain saw bow which includes the following elements:

1. A bow frame essentially circular in shape and having a plurality of spaced apertures around the periphery thereof for mounting;

2. A pair of chain guards, each having one end removably attached to the bow frame; and

3. An engine mount plate in adjustable cooperation with a chain saw and carrying the opposite ends of the chain guards in removable attachment.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood in view of the following description presented with reference to the accompanying drawings.

FIG. 1 of the drawing is a side elevation of the improved chain saw bow of this invention;

FIG. 2 is a front end elevation of the chain saw bow illustrated in FIG. 1;

FIG. 3 is a side elevation of the bow illustrated in FIGS. 1 and 2 with a chain seated and located in functional position;

FIG. 4 is a front end elevation of the bow illustrated in FIG. 3; and

FIG. 5 is a side elevation of a conventional chain saw bow.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIGS. 1 and 2 of the drawing, the new and improved chain saw bow of this invention is generally illustrated by reference numeral 1, with bow frame 2, to which are attached chain guard bases 4 of chain guards 3. The opposite ends of chain guards 3 are bolted by means of chain guard bases 4 to engine mount plate 8, equipped with engine mount plate slot 9 for removable attachment to a chain saw (not illustrated) and oil and adjusting aperture 10, for effecting oiling and tightening of the cutting chain. Bow frame apertures 5 are preferably provided in pairs and in selected spaced relationship around the periphery of bow frame 2, as illustrated, and spurs 7 may be bolted in place with chain guard base 4 of a chain guard 3, by means of bow frame bolts 6. Bow frame bolts 6 also serve to position the chain guard 3 adjacent spurs 7 in position to cover the moving chain as hereinafter described. In the alternative, spurs 7 may be positioned in any of the aperture locations between chain guards 3 to aid the cutting operation, as desired. Engine mount plate bolts 13 serve to bolt the opposite ends of chain guards 3 to engine mount plate 8.

Referring now to FIGS. 3 and 4 of the drawing, chain 11, carrying chain teeth 12, is positioned on bow frame 2 in functional position, and is designed to traverse the periphery of bow frame 2 and engine mount plate 8 as the chain saw engine and cooperating clutch mechanism (not illustrated) are activated. When engine mount plate 8 is fitted into a cooperating receptacle on the chain saw, oil and adjusting aperture 10 is designed to receive oil at predetermined intervals and distribute the oil to chain 11 for lubrication purposes. It will be appreciated that chain guards 3 serve the dual function of positioning bow frame 2 and covering chain 11 for safety purposes.

Referring now to FIG. 5 of the drawing, conventional chain saw bow 14 is illustrated, which bow is typically formed as an integral unit with engine mount plate 8. Chain guard 3 and spurs 7 are designed to be bolted in the appropriate position as illustrated on conventional bow l4, and bow frame apertures 5 are provided for use when bow segment 15 wears to an undesirable extent during the cutting operation. In use, conventional bow 14 is initially fitted with a chain similar to chain 11 illustrated in FIGS. 1-4, and is subsequently mated with a chain saw engine and the chain is then ready for activation. Spurs 7 are next positioned against a segment of wood or a tree to be cut and the chain is activated at high speed in order to effect the proper cutting. Repeated cutting in this manner causes bow segment 15 to wear at a relatively rapid pace in spite of the existence of hardened metal strip 16 which is welded to conventional bow 14 to minimize bow wear. When bow segment 15 abrades to an undesirable degree, spurs 7 must be removed by removing bow frame bolts 6, the bow must then be removed from the engine and the bow reversed top-to-bottom, and spurs 7 subsequently mounted on the opposite side of conventional bow 14 by registering bow frame bolts 6 and bow frame apertures 5. Additional cutting may then be accomplished until a new bow segment 15 is worn adjacent spurs 7, at which time conventional bow 14 must be discarded.

It will be appreciated that frequently during the cutting operation, and particularly when cutting live trees, conventional bow 14 may become trapped between cut segments of the tree, and it becomes necessary to remove the bow by force. During the removal operation the bow is frequently cracked or broken and must therefore be returned to the shop and welded or a new bow substituted in the field. Bow failure also frequently occurs at the point where the bow frame is welded to the engine mount plate due to vibration. Furthermore, when the bow is worn at both spur locations it can no 4 longer be used and must be either reworked at the factory or shop or permanently discarded.

In contrast to the conventional bow illustrated in FIG. 5, and referring again to FIGS. l-4 of the drawing. chain saw bow 1 of the instant invention includes a bow frame 2, equipped with multiple locations for spurs 7 to permit rotation of bow frame 2 from each set of bow frame apertures to the next set as each respective bow frame segment 15 adjacent spurs 7 becomes worn. Typically, and as illustrated, eight such positions for mounting spurs 7 and for affixing bow frame 2 to chain guards 3 may be provided to achieve four times the wear factor of conventional bow 14, illustrated in FIG. 5. Furthermore, it will be appreciated from a consideration of the independent mounting of bow frame 2, chain guards 3 and engine mount plate 8, that if either bow frame 2, chain guards 3, or engine mount plate 8 are damaged, a spare part can be supplied and implemented quickly and easily in the field without necessitating a welding operation or discard of the bow frame, as is necessary in the case of conventional chain saw bows. For example, if bow frame 2 should become caught between the stump and trunk of a cut tree and broken in the removal operation, bow frame bolts 6 can be removed, a new bow frame inserted in place of the broken frame, and bow frame bolts 6 replaced in a very short time. Likewise, if either/or both of chain guards 3 become bent or otherwise damaged, they may likewise be replaced, individually or collectively, with little effort and in a short period of time. Furthermore, in the unlikely event of the warping, cracking or breaking of engine mount plate 8, it too may be replaced by removal of engine mount plate bolts 13, and a new plate can be inserted without undue down time.

It is particularly significant that even in the unlikely event that spare bow frames are not carried in the field by the user, bow frame 2 can still be utilized if broken. For example, if approximately one-fourth to one-third of the bow frame should crack or break, that portion of the bow can be inserted between chain guards 3, bolted in place, and the external portion of the bow carrying the chain will function quite effectively to handle the cutting operation. Accordingly, so long as an undamaged bow frame arc is sufficiently long to bridge the gap between the chain guards and to be bolted in place on the chain guards the bow frame can be used effectively according to the teachings of this invention.

It will be further appreciated that the outer periphery of bow frame 2 is preferably bevelled in order to minimize pinching" of the frame during the cutting operation, and in addition, the chain guards are preferably attached to the bow frame and engine mount plate by means of machine screws or bolts.

Yet another advantage of the improved bow of this invention lies in its susceptibility of being produced through automation. For example, a single bar can be bent in an appropriate jig into the circular configuration illustrated in FIGS. 1-4, and a single weld effected to join the two ends. Multiple holes can then be drilled in one drilling operation and the bow frame can be heat treated by open flame in a short time to achieve the necessary peripheral hardness to carry the chain. Furthermore, the bow frame, chain guards and engine mount plate can be quickly and easily adapted to substantially any chain saw by simply providing engine mount plates of varying design and shape which are compatible with the particular types of chain saws manufactured. Accordingly, after the appropriate engine mount plate is selected, any chain saw can be utilized with the circular bow of this invention.

Having described my invention with the particularities set forth above, what is claimed is:

1. A chain saw bow comprising:

a. a frame having an essentially circular shape of predetermined diameter;

b. a plurality of apertures in spaced relationship in said frame;

c. apair of chain guards, each having at least one aperture at each end thereof carried by said frame at one of said each end; and

d. an engine mount plate carried by the free ends of said chain guards and adapted to removably and adjustably cooperate with the engine housing of a chain saw.

2. The chain saw bow of claim 1 further comprising a mounting slot and an oil and adjusting aperture in said engine mount plate.

3. The chain saw bow of claim 1 wherein said plurality of apertures is 16 apertures in spaced sets of two such apertures each.

4. The chain saw bow of claim 1 further comprising a mounting slot and an oil and adjusting aperture in said engine mount plate and wherein said plurality of apertures is 16 apertures in spaced sets of two such apertures each.

5. The chain saw bow of claim 1 further comprising at least one spur in cooperation with said frame and 6 said apertures to facilitate efficient cutting by said chain saw bow.

6. The chain saw bow of claim 1 wherein said plurality of apertures is 16 apertures in spaced sets of two such apertures each and further comprising:

a. a mounting slot and an oil and adjusting aperture in said engine mount plate; and

b. at least one spur in cooperation with said frame and said apertures to facilitate efficient cutting by said chain saw bow.

7. The chain saw bow of claim 1 wherein said chain guards are affixed to said frame and said engine mount plate with machine screws.

8. The chain saw bow of claim 1 wherein:

a. said chain guards are affixed to said frame and said engine mount plate with machine screws; and

b. said plurality of apertures is 16 apertures in spaced sets of two such apertures each; and

c. further comprising at least one spur in cooperation with said frame and said apertures to facilitate efficient cutting by said chain saw bow.

9. The chain saw bow of claim 8 further comprising a mounting slot and an oil and adjusting aperture in said engine mount plate.

10. The chain saw bow of claim 9 wherein the outer peripheral edge of said frame is bevelled to prevent binding of the frame during the cutting operation. 

1. A chain saw bow comprising: a. a frame having an essentially circular shape of predetermined diameter; b. a plurality of apertures in spaced relationship in said frame; c. a pair of chain guards, each having at least one aperture at each end thereof carried by said frame at one of said each end; and d. an engine mount plate carried by the free ends of said chain guards and adapted to removably and adjustably cooperate with the engine housing of a chain saw.
 2. The chain saw bow of claim 1 further comprising a mounting slot and an oil and adjusting aperture in said engine mount plate.
 3. The chain saw bow of claim 1 wherein said plurality of apertures is 16 apertures in spaced sets of two such apertures each.
 4. The chain saw bow of claim 1 further comprising a mounting slot and an oil and adjusting aperture in said engine mount plate and wherein said plurality of apertures is 16 apertures in spaced sets of two such apertures each.
 5. The chain saw bow of claim 1 further comprising at least one spur in cooperation with said frame and said apertures to facilitate efficient cutting by said chain saw bow.
 6. The chain saw bow of claim 1 wherein said plurality of apertures is 16 apertures in spaced sets of two such apertures each and further comprising: a. a mounting slot and an oil and adjusting aperture in said engine mount plate; and b. at least one spur in cooperation with said frame and said apertures to facilitate efficient cutting by said chain saw bow.
 7. The chain saw bow of claim 1 wherein said chain guards are affixed to said frame and said engine mount plate with machine screws.
 8. The chain saw bow of claim 1 wherein: a. said chain guards are affixed to said frame and said engine mount plate with machine screws; and b. said plurality of apertures is 16 apertures in spaced sets of two such apertures each; and c. further comprising at least one spur in cooperation with said frame and said apertures to facilitate efficient cutting by said chain saw bow.
 9. The chain saw bow of claim 8 further comprising a mounting slot and an oil and adjusting aperture in said engine mount plate.
 10. The chain saw bow of claim 9 wherein the outer peripheral edge of said frame is bevelled to prevent binding of the frame during the cutting operation. 